Mixed steering assistance comprising a torque control loop setpoint-piloted by a position controller intended for path control

Patent metadata

Field	Value
Publication number	US-2017106903-A1
Application number	US-201515317153-A
Country	US
Kind code	A1
Filing date	Jun 19, 2015
Priority date	Jun 24, 2014
Publication date	Apr 20, 2017
Grant date	—

Abstract

A method for managing a power steering system including at least one steering wheel and at least one assist motor, the method including a step of driver torque control, which involves evaluating a driver torque difference that corresponds to the difference between a predefined driver torque setpoint and the actual driver torque actually exerted by the driver on the steering wheel, then determining an engine torque setpoint for torque applied to the assist motor in order to reduce the driver torque difference, the driver torque setpoint being generated during a trajectory control step, which involves evaluating a trajectory difference, for example a position difference, which corresponds to the difference between a trajectory setpoint, of the position setpoint type, which depends on a reference trajectory, and the actual trajectory of the vehicle, given by the measured position of the power steering, then determining, from the trajectory difference, a driver torque setpoint intended to reduce the trajectory difference.

First claim

1 . A method for managing a power steering comprising at least one steering wheel and at least one assist motor, said method comprises a driver torque control step (b), comprising measuring the effective driver torque which is actually exerted, at the considered instant, by the driver on the steering wheel, and then comparing said effective driver torque to a predetermined driver torque setpoint in order to assess a driver torque deviation which corresponds to the difference between the effective driver torque and said driver torque setpoint, and then determining, from this driver torque deviation, a motor torque setpoint intended to be applied to the assist motor in order to reduce said driver torque deviation, and in that the driver torque setpoint which is used during the driver torque control step (b) is generated during a path control step (a) that comprises measuring the effective value of at least one parameter called <<path parameter>>, which is representative of the effective path of the vehicle, and then comparing this path parameter to a path setpoint, which is predetermined depending on a reference path that the vehicle is desired to follow automatically, in order to assess a path deviation which corresponds to the difference between said path setpoint and the effective value of the path parameter, and then determining, from this path deviation, a driver torque setpoint intended to reduce said path deviation.

2 . The method according to claim 1 , wherein, during the path control step (a), the effective position of the power steering is measured, and then this effective position is compared to a position setpoint, which is predetermined depending on a reference path that the vehicle is desired to follow automatically, in order to assess a position deviation which corresponds to the difference between said position setpoint and the effective position of the power steering, and then, from this position deviation, a driver torque setpoint, intended to reduce said position deviation, is determined.

3 . The method according to claim 1 , wherein the path control step (a) comprises an output saturation substep (a1) comprising comparing the driver torque setpoint a predetermined admissible maximum threshold, called <<driver torque saturation threshold>>, and limiting the driver torque setpoint to the value of said driver torque saturation threshold if said driver torque setpoint exceeds said saturation threshold.

4 . The method according to claim 3 , wherein the driver torque saturation threshold is comprised between 1 N.m and 4 N.m.

5 . The method according to claim 1 , wherein the path control step (a) comprises using a driver torque setpoint determination law, in order to determine the driver torque setpoint from the path deviation, wherein said driver torque setpoint determination law is in the form of a function centered on the path setpoint, and associates to every effective value of the path parameter, a corresponding driver torque setpoint.

6 . The method according to claim 5 , wherein the function that is representative of the driver torque setpoint determination law is a curve called <<S-shaped>> curve presenting an increasing central domain which is centered on the path setpoint, wherein said increasing central domain is surrounded by two asymptotic domains with a slope that is lesser than the slope of the central domain, or even with a slope that is substantially zero.

7 . The method according to claim 1 , wherein the path control step (a) comprises using an automatic piloting function for parking maneuver or an automatic piloting function for following a traffic lane, in order to determine the path setpoint.

8 . A data medium readable by a computer and containing computer program code elements ensuring the execution of a method according to claim 1 when said medium is read by a computer.

9 . A power steering management module comprising a driver torque control module, which receives in input, on the one hand, a driver torque setpoint and, on the other hand, a measurement of the effective driver torque which is actually exerted, at the considered instant, by the driver on the steering wheel, which assesses a driver torque deviation which corresponds to the difference between the effective driver torque said driver torque setpoint, and which provides, in output, depending on said driver torque deviation, a motor torque setpoint, intended to be applied to the assist motor in order to reduce said driver torque deviation, said management module also comprising a path control module which receives, in input, a path setpoint which is predetermined depending on a reference path that the vehicle is desired to follow automatically, as well as a measurement of the effective value of at least one parameter called <<path parameter>>, which is representative of the effective path of the vehicle, and wherein said path control module then assesses a path deviation which corresponds to the difference between said path setpoint and the effective value of the path parameter, and then provides, in output, connected to the corresponding input of the driver torque control module, a driver torque setpoint determined from the path deviation and intended to reduce said path deviation.

10 . The power steering management module according to claim 9 , wherein the path control module receives, in input, a position setpoint which is predetermined depending on the reference path that the vehicle is desired to follow automatically, as well as a measurement of the effective positions of the power steering, and then assesses a position deviation which corresponds to the difference between said position setpoint and the effective position of the power steering, and then provides, in output, connected to the corresponding input of the driver torque control module, a driver torque setpoint determined from the position deviation and intended to reduce said position deviation.

Assignees

• Jtekt Europe Sas

Inventors

• Moretti Romain
• Leydier Luc

Classifications

• B62D5/0472

  for damping vibrations · CPC title

• B62D5/0463

  calculating assisting torque from the motor based on driver input · CPC title

• B62D1/28 Primary

  non-mechanical {, e.g. following a line or other known markers} · CPC title

• B62D1/286

  Systems for interrupting non-mechanical steering due to driver intervention · CPC title

• B62D6/00 Primary

  Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits (means for initiating a change in direction B62D1/00; steering valves B62D5/06; combined with means for inclining the vehicle body or wheels on bends B62D9/00) · CPC title